1. Field
The invention relates to graphical representation of product structures subject to effectivity constraints. More specifically, the invention relates to graphical representation of product structures subject to validity constraints.
2. Background
To support traceability and preserve history of an iterative development, all changes need to be captured. This is equally true for product development. Commonly, these changes are captured as change states. As used herein, “change states” are the smallest, i.e., most granular, atom of history. Traditionally, they have been distinguished from one another by a change number, which is unique for each iteration. Commonly, a subsequent iteration of a change state is created as a copy of the predecessor with one or more attribute fields changed. The unique change number indicates the new change state and assigns an effectivity. Herein, “effectivity” is used synonymously with validity.
Effectivity can be, for example, date effectivity or parameter effectivity. The effectivity is typically stored in a change master. Accordingly, the change master retains the effectivity globally for all related change states. With respect to date effectivity, it is commonly represented as an open interval, e.g., a valid from date. Date effectivity is typically closed by the creation of a subsequent change state with a subsequent valid from date. With parameter effectivity, it is possible to have a single value, a closed interval (a start and end value) or an open interval, which merely has a starting value. Again, open intervals are deemed closed by a subsequent change state having its own effectivity interval.
Historically, viewing of the change states required selection of the effectivity parameter value for which viewing was desired. The change states effective at that value would then be returned to the user for viewing. Thus, what was returned was merely a snapshot of the product structure consistent with the selected parameter value. This fails to provide a historical context of changes in the product structure.